The MG-B that Dr. Wheeler drives in the opening scene with a tan interior and a black plastic honeycomb grille switches to an earlier model with a black interior and an all chrome grille (noticeable in the scene where the car will not start). When Dr. Wheeler visits the Jefferson Institute, it has switched back to the MG-B with the tan interior and black grille.
When Dr. Harris completes an appendectomy, the anesthesiologist reaches for the patient's endotracheal tube, as Dr. Harris begins to turn away. When he completes the turn, the anesthesiologist is seen removing a face mask from the patient. There was no time for the anesthesiologist to remove the tube and replace it with the mask.
When Mark puts Dr. Wheeler to bed after the chase at the Anatomy Lab, the bed covers change between when she lays down and when she leaves moments later.
At around 1:26:47, when Mrs. Emerson tells Norman about the electrical inspection, the numbered blocks in her desktop calendar change between shots.
[Theatrical version only] In the room where the coma 'patients' are suspended, there are several topless women clearly visible. Not too much later, there is a shot of the guards in the coma room chasing Susan, and the women's breasts are covered. a few minutes after that, in the next shot of the room, the women are topless again.
When Dr. Wheeler discovers the carbon monoxide line leading to OR 8, it might seem as if she is looking down into the operating room, but she is actually above the hall looking at the door into the OR, as the sign plate beside the door indicates. An operating room would never feature a drop ceiling.
Dr. Wheeler sprays a man with a fire extinguisher, completely covering his head, face and upper torso with the dry white fire retardant. Only seconds later, the same man chases her and stops to look for her. He now is totally clean; not a trace of the powder on him. The fire extinguisher Dr. Wheeler used is a CO². The white substance is frost which will melt quickly.
Dark-haired stuntman falling down the stepped aisle of the lecture theatre, in place of fair-haired villain.
Although the background passenger on the MBTA might look like a dummy, she is obviously real. She moves her eyes during the scene.
When the anesthetist opens Nancy Greenly's right eye to check her pupil, her startle reflex makes her left eyelid move, giving away the fact that she's not unconscious.
When Dr Wheeler first turns on her small penlight to follow the gas line, the light shining on the line is from a large flashlight. While Wheeler holds her penlight fairly steadily, the light it is supposedly emitting shakes a lot, and also casts a shadow that shouldn't appear at the angle from which she is pointing her light. The spot of light is also huge compared to later shots where the light spot is relatively and correctly dimmer and smaller.
Ladder from the maintenance shop up the pipe chase passageway starts being painted red, and turns black farther up.
Drs. Mark Bellows (Michael Douglas) and Susan Wheeler (Geneviève Bujold) are seen on the DVD cover/movie poster climbing a ladder together, presumably the one that leads to the crawlspace above OR8. Each one of the characters only climbed a ladder once and those were on separate occasions.
The ambulance driver states that he has to go through the Sumner Tunnel to get to Logan Airport. Since 1961, the tunnel going to Logan has been the Callahan tunnel. The Sumner tunnel has been outbound from the airport since 1962.
Crew and a camera are reflected in the glass as we first see Mrs. Emerson approach Dr. Wheeler.
Dr. Wheeler and Dr. Bellows are walking along a corridor discussing something. A technician must be moving along the floor with a long microphone which can be seen.
At approximately 1:43:07, Dr. Wheeler reaches over and triggers Dr. Bellows' pager, he tells Dr. Harris that he has to answer his page. The shadow of the boom can be seen on the wall behind them (upper left corner). The shadow follows Michael Douglas as he walks out of frame and then the shadow comes back into frame and follows Richard Widmark.
At the Jefferson Institute all of the patients are very young and fit, but nothing seems to be made of this from the tour group.